Bicycle coaster brake



June 14, 1949. H. A. SHERWOOD 2,473,177

BICYCLE COASTER BRAKE Filed July 25, 1947 2 Shee ts-Sheet 1 IN VEN TOR.

A TTO/Q/VEYS' Patented June 14, 1949 item 3 Claims. 1

:This'invention-relates tobicycle coaster brakes which qpe'rmitithelrider to coast without .pedaling Qand'to .br-ake. by back pedaling.

I OneIobject is to. provide an arrangement for 'frictionally'retardinguthe rotation of the operatflling nut of such a brake, which does not usemetal spring elements .andtwhich' provides non-metallic .ifricti'onalsurfaces of less elasticity but greater .elasti'c' deformability than metal and" which are oilmaximumlareasifi This operating tnut rides a screw connecting with .the sprocket wheel worked by the bicycle pedals, and; functions with" forward l pedalingtoclutch the sprocket wheel tolthe'bL cycle hub to drive the bicycle during" which time .the nut must turn with. the hub-." When pedaling stops thenutscrews itself along the screw to' efiect 1. declutching 'soi'the bicycle coasts, and upon back -pedaling the nut is screwed farther along to providebrake-applying force'LThe nut must befrietionally retarded from turning with thescrew, vfor it to performitheseioperating functions, and this .must be done frictionally since the nut must turn during the'transmission 'of. 'drivingforce to the hub. Metal spring elements are usually used, in the form of frictional fingers andlpthel like, but these are subject t'o'fatigu'efailure an'd'are'therefore unreliable. Heretoforel frictional surfaces "'t'provided by non-metallic material-f easy elastic deformability as exemplified, by soft rubber, cork, and the like," have been usually avoided'because fthe-prior art could'notprovide large enough fricti'onallyinterworkingvareas to obtain good service life.

' Another. object is to provide'a'ybicycle' coaster brakeincorporating ailock'in its construction, which positively locks the hub 'againstrotation for theft prevention in'such 'a'm'anner'that the ,bicyclecannot be damagedsh'ould an effort be made *--to operateit'whenthe lock is on. In'this connection; an-equally important object is tonincorporate a -lo'ck'into the "construction.ofabicycle coaster brake in such a manner 'that'anytendency for it tolockwhile' the bicycle is in." operation is either prevented; or is attended by a warning to' the "'f bycyclist.

- A specific example of 'abic'ycle coaster brake incorporating the prin'ciplesiof the invention is i'.illustrated by I the accompanying...drawings in which:

. Fig; I is a half-sectioned isideiyiewl-i 'ofathis 5 .6 encircle the ax1e. Thevsprocketwhub firruns freely on ball bearings 1 in a raceway-formed by .the inner facet'of' the sprocket hub, and theouter l :face'of aZbearing. nut 8 screwed onthe'lother .threaded end 2 of the axle I. .The sprocket-hub Band'the bearing nut 3 have. outer: peripheral "LpOrtionsand the .wheelhub 5 hasinner peripheral portions respectively providing raceways. for 'ballilbealtings 9 journaling thewheel hub. [ff'The bearing nut 3 and bearing nut 8 .areiscrewed together .to get the properbearingadjustment. 3 The :Jsprocket hub 61 and therwheelhub 15 .canfreely rotate relative each other and, relative theaxle l,"while the latter and the .bearingnut 3.are sta- I tionary ;relativ' the, .bicycle frame.

A hollow screw lt concentrically encircles the axle landis in theformof alcantilever extension'of'the sprocket hub ,6, so this. screwisnrota- .tiVelyJfree relative the axle'and wheelhub. A brake andclutch eontrollinglnut ll is-threa-ded onithis screw [0, its outer periphery having an i 'outwardlylfacing .clutchcone 2 engaging a clutch c'onel3 on the inside of..the adjacent end-otthe "iLwheel hub 5i when.ithez nut ll screws outwardly,

ahdan inwardly facing'brake shoe operating: cone "'l4'-,for working, the brake elements when the nut screws inwardly. The bearing-nut 3"hasan in- .rwardlyextending cantileverhub t5 integral-therewith and ,providingsan inwardly extending'brake operatingcone ItIan-d longitudinal guideways l! inwardly extending therefrom. Brake shoe segiments l 8 .encirclethis hub 5 withintegra-l guides lfl'riding .inlthe guideways l 7,; and mutually oppossitehinclined endsellisfor icooperation :withiithe .conessand-16.- :These segments haveibraking irsurfaces zl which-bear against axbrake druni 22 .1 formedomtheunside of :thewheel 'hub 5. A :clip i ,ring-t23fifits aperipheral'groovein the innerlend ,oithe lcantileverihub" I 5, and limits inward slidsing of: the :brake-,-shoes 18, by: forming abutments i in .thebnake: shoe' guideways l1.

1 nThes usual sprocket 24 is screwed ontoxthe sprocketthubicwand locked by asprocket lock nut 14a .Thereforeuwhen :the :bicyclistpedalsf,';the vsprocket 6-receives the" operatingzforce. 'Ifst'he -;c0ntro1l -ing nut H is restrained fromrotating'with A vthenscrewi 0; with the-restraint atcleast sufiicient r. vto overcome: athe: :screw; frictionxrwith forward pedaling this .controlling .nut l l; screws outwardly so that its clutch cone I2 engageslthexclutchrcone laionithet-msidebtithea-diacentiend otzthezwheel hub 5. In that event, the driving force is properly transmitted to the wheel hub 5 to drive the bicycle. If the bicyclist stops pedaling, the screw I stops rotating while the nut II continues to be turned by the interengaging clutch cones, due to the bicycle coasting and continuing to turn the hub 5. This screws the nut II inwardly until the clutch cones separate, whereupon free-wheeling coasting occurs. Back pedaling turns the screw III backwardly and, if the control nut II does not turn due to a restraint previously described the nut I I screws itself inwardly so that its brake shoe operating cone I4 wedges the brake shoe segments outwardly by working against their adjacent inclined ends 20, while applying longitudinal force causing their other inclined ends 20 to be wedged outwardly by the inwardly extending brake operating cone I6 of the bearing nut 3. Forward pedaling screws the nut II outwardly to relieve this wedging action so that the brake shoe segments release, the nut then being again in freewheeling coasting position.

Obviously the operation of the brake depends entirely upon the use of some device to prevent or retard the control nut I I from turning with the screw Ill, because this control nut cannot be screwed in either direction from its coasting position, if the control nut turns with the screw Ill. The prior art has never provided a complete solution to the apparently simple problem of providing a rugged arrangement for preventing the control nut from rotating with the sprocket hub screw without interfering with the operation of the other elements.

The first mentioned object noted at the beginning of this specification, is attained by providing a cantilever hub 25 fixed to the inner end of the nut I I, with a bore having a diameter substantially larger than that of the axle I and with this hub 25 encircling the latter. This hub 25 projects from the nut I I into the annular space inside the hub I provided by reason of the latter having a cylindrical bore I511. with a diameter sufiiciently larger than the diameter of the axle I, and the outside diameter of the hub 25, to provide the necessary annular space. The outside of the hub 25 carries a sleeve 25 having a cylindrical outside and made of material having easy elastic deformability in the nature of soft rubber or cork, the term rubber being used to embrace the natural and synthetic products. This material is interposed between the mutually adjacent peripheral surfaces of the two cantilever hubs I5 and 25 and could be fixed to either while being, of course, free from the other. it is easier to fix it to the hub 25 with the cylindrical outside of the sleeve 26 frictionally Working against the cylindrical bore I5a of the hub I5, and an important advantage of this arrangement is that full advantage is taken of the invention for providing the maximum possible frictional surface areas for working together. The sleeve may be simply slipped over the hub 25 and retained by friction. The hub 25 should be made fairly long since the longer it is the greater is the frictional areas that can be provided. The necessary, axial movement of the nut II is easily permitted, the hub 25 sliding inside the bore I5a of the hub I5 in an axial direction. The nut is frictionally restrained from rotation, because the outside diameter of the sleeve is slightly larger, when the sleeve is unstrained, than the diameter of the bore I5a, so frictional contact with the bores inside is effected.

The nut II is provided with a counterbore 21 However, if fixed to either in its inner end facing the hub I5 and the hub 25 has its end adjacent the nut, provided with a stout flange 28 pressed into this counterbore to effect the mounting of the cantilever hub 25 by the inner end of the nut I I. The hub 25 and its flange 28 may be made of metal.

It is to be noted that the hub I5 is not an extra part but is required for the function of providing a proper mounting for the brake shoe segments I8. This normal function is not interferred with in any fashion by the hub 25 working in it nor is any unusual force transmitted to the brake segments. Any small amount of heat that might be generated during the rotation of the hub 25 relative the hub I5 with the mom-metallic sleeve 25 interposed and its exterior frictionally sliding on the interior of the hub I5, is easily dissipated since the hub I5 has a direct metallic thermal circuit from it to the bearing nut 3 which is tightly clamped to the bicycle frame and to the brake arm 4. The heating effect is well distributed, in any event, due to the broad frictional areas producing it. The heat cannot be transmitted to the nut II to cause its possible binding, since the non-metallic material 26 is a poor heat conductor, and there is no direct metallic thermal circuit between the hub I5 and the nut II, the circuit being by way of the brake shoe segments I8 which are in relatively loose engagement with the hub I5 and the inner end of the nut II, if they actually contact the nut at all, during the driving operation of the coaster brake assembly. Heat is not transmitted easily through loose connections.

It is considered preferable to make the sleeve 26 of cork. This material is noted for its long wear when used for frictional drives. It is not ordinarily used for coaster brake assemblies, for the same purpose, because the prior art has not provided any arrangement permitting adequately large interworking frictional surfaces. This defeet in the prior art now being overcome by the present invention, it becomes practical and desirable to use cork. However, either synthetic or natural rubber may also be used.

The construction of the brake, and of many prior art coaster brakes, provides the brake arm 4 for fastening to the bicycle frame, and an adjacent spoke hub which mounts the wire spokes of the bicycle wheel. The lock of the present invention is provided by forming the brake arm 4 with a depending shoulder 4a and providing a transverse guideway 21 in this shoulder to. Preferably this guideway is surrounded by an inwardly extending housing 28 so that the guideways length is greater than the normal thickness the brake arm 4 would otherwise provide. A reciprocative lock 29 is mounted in this guideway 27 and is adapted to be pushed inwardl to lock the wheel of the hub 5 or moved outwardly to release the wheel for rotation.

This lock is preferably of the type that is springbiased outwardly to its inoperative position and which in addition can be locked in either its operative or inoperative positions. This is in the interest of safety, the provision of a lock on a bicycle coaster brake being normally considered a dangerous thing because of the liability of it looking during the operation of the bicycle.

In the case of the present invention the part of the hub 5 that provides the spoke hub is extended radially outwardly to provide a disk ring 30 extending radially outwardly to be opposite the lock 29, and it has a plurality of holes SI formed transversely through it in the form of an annular series so each hole registers with the lock 29 as the disk ring turns. The lock 29 is preferably provided with a projecting stud 32 of slightly smaller diameter than the holes 31 and its inner end is preferably beveled as at 33. I

The above arrangement is of importance because should the lock fail to remain in its outer position for any reason, it cannot gravitationally move to looking or operative position, because of its horizontal arrangement. However, it might tend to drift to a locking position, but should this occur while the bicycle is operating at a speed fast enough to cause a bad accident should looking inadvertently occur, the various holes 3i are at that time rotating rapidly past the stud 33 so the latter cannot move into a locking position in any one of the holes. The beveled end 33 further contributes to this result by its natural cam action. At the same time, as the stud 32 drifts to a dangerous position and while it is being prevented from going farther as just described, it makes a clicking noise as the holes 3| of the disk ring 30 revolve past it with the rotative speed preventing the stud from moving fully into any one hole. This immediately warns the bicyclist of the danger and he can stop and fix the trouble.

It is apparent from the foregoing that the lock provided by the present invention is completely safe for use and is positive in action since it engages the disk ring 30 directly with the brake arm 4 which is in turn securely fastened to the bicycle frame in the usual manner. It is impossible to damage the bicycle should an attempt be made to steal it. With the usual lock consisting of an ordinary padlock with an appropriately large hasp, the usual practice is to apply the lock in such a fashion that the spokes of the bicycle wheel are broken when an attempt is made to steal the bicycle. This trouble is avoided by the present invention. The obvious convenience of having a built-in lock is also enjoyed.

I claim:

1. A coaster brake including a stationary axle, a hollow screw rotatively encircling said axle and receiving the operating force, a hub rotatively encircling said axle and screw with an inwardly facing clutch cone adjacent said screw, a nut screwed on said screw with its outside having an outwardly facing clutch cone cooperating with said clutch hub cone and an inwardly facing brake operating cone, a stationary inwardly facing brake operating cone encircling said axle and spaced opposite said brake operating nut cone, a plurality of brake shoe segments encircling said axle between said brake operating cones with operating ends cooperating therewith so said segments can be wedged radially into contact with the inside of said hub, guides rotatively locking said segments relative to said stationary brake operating cone while leaving them free for longitudinal and radial movement, and a device for at least retarding rotation of said nut and positioned entirely between it and said axle and free from said brake shoe segments and said hub, said guides being formed in a cantilever hub nonrotatively encircling said axle and extending toward the adjacent end of said nut, and said device comprising a hub fixed to said end of said nutand projecting inside the first-named hub, the latter having a bore for receiving the secondnamed hub and the adjacent surfaces of the two frictionally interengaging.

2. The coaster brake defined by claim 1 with material having easy elastic deformability in the nature of soft rubber or cork interposed between the adjacent surfaces of said hubs and efiecting their frictional interengagement.

3. The coaster brake defined by claim 1 with said nut having a counterbore in its end facing the first-named hub and with the second-named hub mounted in said counterbore.

HENRY ALLAN SHERWOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

